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Scott Davis

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Posts: 697
Reply with quote  #1 
The vented soffit solar hot air collector works very well, almost as well as the screen design.  It is more expensive to build than the screen and requires more construction time (painting the soffit, cutting it, gluing it together with silicone caulk, etc).

There are the steps Gary used to build the aluminum soffit solar hot air collector:


Have you built a vented soffit solar hot air collector? Please reply and tell us about it here! Please be sure to include pictures if you can!

Do you have questions about the vented soffit solar hot air collector? Please reply, this is the place to ask about it! We will do our best to help!

Take care, Scott MD

kenneth w

Posts: 3
Reply with quote  #2 
This is the soffit collector I make. I hope the picture come thru


This is my homemade solar hot air collector. If you are looking for a super cheap collector this is not for you. But if you are looking for a lower cost easy to build long lasting collector that you will be proud of, this might be what you are looking for.


This collector has;

No wood is used in the collector.

This collector is a matrix collector.

Vented aluminum vented soffit for the absorber matrix

Twin wall polycarbonate glazing

A metal stud track frame


 Material list and prices 10/10/10

1-4x8 sheet of 6mm twin wall polycarbonate                  $40

 (bought at Menards)    

2-4x8 sheets of 1” polyisocyanurate insulation               $27

 (the yellow stuff with foil)

2-16’x12’ full vent aluminum soffit or 4-half vent         $30 

3-5 ½ stud track 10’long                                                  $?

(A alterative is 2 PVC 6x6 post cut length wise )

1-can of primer and 1-can of color paint for frame         $10

1-can of flat black barbeque grill paint                            $5

1- Snap switch                                                                  $15

 (a thermostat that turns the fan on and off)

A used furnace exhaust vent fan                                      ?

 short metal screws and 8 screws with rubber washers

For a total of around       $200


The way this kind of collector works is the air enters the bottom from the back. The air then it deflected from the hitting the glazing with a baffle plate (next to the glazing). The air will flow up and through the soffit absorber plate striping the heat off the soffit. The air (now hot) flows up behind the soffit and out the top back of the collector.       



The collector it a sandwich of the glazing, a foam spacer that holds the soffit, and the back insulation held to gather with the stud track


Here is a cutaway of the sandwich

The glazing (front of the collector) on the left

The foam spacer with the soffit (inserted ½ “into it)   in the center

The insulation panel on the right

The stud track holding it all together

The half vented soffit is on the right

The half vented soffit with the non-vented part cut off is in the middle

A piece of the stud track is on the left

If you can’t find the full vent soffit you will have to cut the non-vented part of the soffit off with a tin snips

The soffit is cut 1”shorter then the glazing is wide 48”-1”=47”

Then painted flat black on one side  Then lay the soffit panels out so that they form the finished  absorber panel which is 47” x about 7” less then 8’ (it will vary depending to the soffit material)    The 8” will be at the bottom of the collector so that you can install the air intake. Use three screws per joint to fasten the soffit pieces into the absorber panel




The stud track makes up the frame of the collector if the track has a extra long legs you will want to put a piece of insulation in the stud rail to make the remainder of leg a little over 1” ( on mine I user ¾ insulation)

Cut the vertical (sides of the collector) stud track the length of the glazing + twice the leg spacer insulation. On mine it was 8’ 1 1/2'” long.

 The top cap piece of stud track is cut the width of the glazing + twice the leg spacer insulation + twice the height of the stud track leg length and a little to fit over the side pieces. So on mine it is 48” +(3/4x2) 1 ½ “+(2x2) 4”=53 ½”+ ¼”

The bottom inside piece is the same 53 ½”but – ¼ “

I hope that not to confusing.


Now you can cut a slot in the ends if the cap stud track and the bottom stud track so the end can be folder over. The cuts should be cut from the end on the leg of the track so that when folded over the corner of the stud track will cover the corner of the fold.



Stud track with the cut from the end on the legs next to the corner. The sides are folded in


Bending the top down


Inside after bending

Paint the 4 pieces of stud track the color of your choosing (I herd that if you wash galvanized steel with vinegar before painting the paint will stick better)



Outside of the cap.  The top corners over lap the seam.

Next the insulation spacer pieces.

The 4 pieces will be cut to a width so that it will fit snugly inside the stud rail between the glazing and the back insulation. (refer to the second picture) The 2 side pieces will be the length of the glazing            96” - 2” = 94”   The top and bottom will be the same as the width of the glazing 48”






Next cut the ½” deep grooves for the soffit.

The baffle slot will be a ½” from the glazing on the bottom of the side pieces. The groove for the absorber plate (soffit) will be at a angle going a ½”  from the glazing on the top of the collector to the back of the collector near the bottom you will have to measure the absorber panel to get the length from the bottom (about 10”? ) You will want the bottom of the absorber to be tight to the back insulation panel.



Looking from the glazing side.

The absorber (soffit) and baffle inserter into the side insulation  


Looking into the bottom of the collector with the stud track on the side.

From the left you have the glazing, baffle, absorber, and the back insulation.


With all the parts ready you can insert the baffle and the absorber panel into one of the side insulation pieces then put the other side insulation on the other end of the baffle and absorber panel. Put the glazing on front side and the back insulation on the back side and work the side stud rail over the sandwich. Hold together and flip over and work the other side stud rail on. Now you can put the top insulation in place and put the top cap on. Then put the bottom insulation in place and put the bottom stud rail between the side stud rails.

Now you will put 2 screws into the 4 corners to hold the collector together.


All you have left to do is mount the collector and cut the holes for the intake the out put holes



Posts: 2
Reply with quote  #3 
Hi Scott,

Why you do not put an aluminum reflective foil on insulation. That would reflect the infrared beam to the vented soffit, not ?
Like this collector -> http://www.apper-solaire.org/Pages/Experiences/Isabel%20Guy%2049/La%20SAGA%20de%20mes%20capteurs%20solaires%20a%20AIR/index.html

(it's not me, I didn't make this collector)
Scott Davis

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Super Moderator
Posts: 697
Reply with quote  #4 
Hi Pop,

In the case of the vented soffit collector, all the insulation is under the soffit, so none is hit by the sun's rays. In the case of other collectors, it is possible that either approach will work, but the fear is that some of the light will be reflected all the way out, and therefore lost.  When the light hits the insulation, it still gets hot.  As air passes over it, the air collects that heat.

Take care, Scott MD

Posts: 7
Reply with quote  #5 
Infrared reflected

Posts: 11
Reply with quote  #6 
A solar hot-air collector can be used to heat your home with renewable energy. The general idea is that as air goes through the solar panel, the sun’s heat naturally increases the temperature of the air.
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